This invention relates to a pipe connection device for connecting and disconnecting a pipe of pressurized fluid such as compressed air to and from a supply inlet of a utilization device such as machine tool or testing equipment and, especially, to such device provided with an automatic valve built therein and arranged to complete connection by only pressing against the inlet of the utilization device and completely shut off leakage of the fluid after disconnection.
An example of the pipe connection devices of this kind is disclosed in the Japanese patent publication No. S53-3747 which is cited herein as a reference. As shown in FIG. 1, this device includes first and second connectors 1 and 2 which are facing each other and capable of relative forward and backward movement. The first connector 1 includes a cylindrical valve body 4 being fit slidably in a circular hole 6 formed therein and having a central passageway 8 and the second connector 2 has a passageway 10 smaller in diameter than the passageway 8, which is formed coaxially with the passageway 8 and connected to the utilization device. The central passageway 8 in the valve body 4 is opened to the side face of the valve body 4 through lateral holes 12 penetrating the side wall thereof. In the drawing, the lower end of the slide hole 6 connects with a cylindrical cavity 14 having a larger diameter than the slide hole 6 and opening at the bottom face of the first connector 1, and the lower end of the cavity 14 is closed with a plug member 16 and a stop ring 18. The plug member 16 has a central screw hole 20 for connecting a pressurized pipe (not shown) thereto. The valve body 4 and the plug member 16 have annular grooves formed in their side faces and O-rings 22 and 24 fit respectively therein for preventing leakage.
An annular sealing member 26 having an outer diameter larger than that of the valve body 4 is attached to the lower end of the valve body 4 and supported by a stop ring 28 fixed to the bottom of the valve body. The valve body 4 is constantly urged upwards by a spring 30 inserted between the valve body and the plug member 16 and the sealing member 26 is thereby pressed against a valve seat 32 formed at the upper end of the cavity 14 to form a closed valve state. An annular groove is formed in the upper end of the side wall of the valve body 4 and an O-ring 34 is fit therein and further fixed by spreading the upper end of the passageway 8.
When the second connector 2 is moved downwards from the position as shown, its lower face abuts first against the O-ring 34 to complete air-tight coupling between the passageways 8 and 10 and, next, the valve body 4 is pushed down against the spring 30 to open the lateral holes 12 into the cavity 14. Thus, an open valve state is achieved and the pressurized pipe (not shown) connected to the screw hole 20 is connected to the utilization device. If the second connector 2 is moved upwards from this state, the valve body 4 is pushed up by the spring 30 to press the sealing member 26 against the valve seat 32 to form a closed valve state. The lower face of the second connector 2 leaves thereafter the O-ring 34 of the valve body 4 and, therefore, the pressurized fluid in the cavity 14 does not leak out at all.
In this connection device, however, the side wall of the valve body 4 needs a substantial thickness since the annular groove is formed in the end face of the side wall and the sealing O-ring is fit therein and, moreover, the length of the device is longer than the total length of the valve body 4 and the spring 30 since they are arranged in series. In other words, this device has such a disadvantage in that the axial and diametral sizes thereof cannot be reduced over the above-mentioned limit due to its structural cause. This problem may be fatal when a plurality of such connection devices are to be arranged within a narrow space for use.
Accordingly, an object of this invention is to provide an improved pipe connection device having a novel structure which can significantly reduce the above-mentioned axial and diametral sizes.